Thread cutting device for circular knitting hosiery machines



Feb. 24, 1970 P. CONT! 3,496,738

THREAD CUTTING DEVICE FOR CIRCULAR KNITTING HOSIERY MACHINES Filed Sept. 20, 1967 3 Sheets-Sheet 1 Fig.1

IN VEN TOR PAoLo MNTI Feb. 24, 1970 P. CONT! 3,496,738

THREAD CUTTING DEVICE FOR CIRCULAR KNITTING HOSIERY MACHINES Filed Sept. 20, 19 3 Sheets-Sheet 2 4 N VVENTM m an NT/ Feb. 24, 1970 P. NT| 3,49

THREAD CUTTING DEVICE FOR CTRCULAR KNITTING HOSIERY MACHINES 3 Sheets-Sheet 5 Filed Sept. 20, 1967 United States Patent C 3,496,738 THREAD CUTTING DEVICE FOR CIRCULAR KNITTING HOSIERY MACHINES Paolo Conti, Florence, Italy, assignor to G. Billi & C. bSocieta per Azioni, Florence, Italy, an Italian corporate ody Filed Sept. 20, 1967, Ser. No. 669,102 Claims priority, application Italy, Sept. 30, 1966, 22,525/66 Int. Cl. D04b 9/46 US. Cl. 66140 Claims ABSTRACT OF THE DISCLOSURE A circular knitting machine for hosiery and the like having a rotatable welt-hooks plate and needle cylinder, has a thread cutting device comprising a peripherally toothed member rotatable with the welt-hooks plate for engagement with a thread to be cut, a stationary blade cooperative with the toothed member to shear a thread extending between a needle of the needle cylinder and a thread guide of the machine and means movable to advance the toothed member relative to the needle cylinder when the thread has been engaged by the toothed member thereby to decrease the inclination, relative to an axial plane of the machine through the needle, of the portion of thread extending from the needle to the toothed member and so to shorten the thread portion.

The invention relates to a thread cutting device for a circular knitting hosiery machine or the like.

According to the present invention there is provided a circular knitting machine for hosiery and the like, having a rotatable welt-hooks plate and needle cylinder and a thread cutting device, said device comprising a peripherally toothed member rotatable with the welthooks plate and capable of engagement with a thread to be cut, a stationary blade cooperative with said toothed member to shear a thread extending between a needle of the needle cylinder and a thread guide of the machine, and means movable to advance the toothed member relative to the needle cylinder when the thread has been engaged by the toothed member thereby to decrease the inclination, relative to an axial plane of the machine through said needle, of the portion of thread extending from the needle to the toothed member and so to shorten said thread portion.

The invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 is a partly sectioned side view on a plane passing through two control shafts of a welt-hooks plate and a thread cutting device in accordance with the invention;

FIGURE 2 is a plan view taken in the direction of arrowed line IIII of FIGURE 1;

FIGURE 3 is a side view similar to that shown in FIGURE 1 but illustrating the device in its usual operational arrangement with the hooks plate in a raised position rather than a lowered position as shown in FIG- URE 1;

FIGURE 4 is a view similar to that shown in FIG URE 2, but partly sectioned; and

FIGURE 5 illustrates a detail of FIGURE 1 to an enlarged scale.

In the drawings, a structure 1 carries a welt-hooks plate 3 which is rotated by a shaft 5 substantially synchronously with a needle cylinder (not shown) coaxial "ice with the plate 3. The shaft 5 is driven from a shaft 7 which, in the plate actuation arrangement, is in a horizontal position. The plate 3 lies adjacent to and is associated with a stationary structure 3A, which, in turn, lies adjacent to and is associated with an intake mouth 3B of a pneumatic intake conduit 3C for the picking of thread, from the thread guide 9, which has been cut. The thread ends are picked up in a space defined between the members 3A and 3B by suction. In a known arrangement, the thread can be taken by, a needle when the thread guide is lowered, and the plate 3 can be raised and lowered according to the various stages of a knitting cycle of a stocking. In particular the plate 3 is lowered (see FIGURE 1) in the stages during which cutting of the thread occurs and is raised (see FIGURE 3) during the stages wherein no such cutting occurs. Thread cutting, when the plate is lowered, is effected nearer the end of the thread engaged by the last needle which has taken the thread, and thus the sheared thread ends extending from the knitted fabric are relatively short. In such an arrangement, the residual thread lengths are not always acceptable from the aesthetic viewpoint in stocking manufacture and the like. The raising and lowering control of the plate (which plate must continue to rotate while the members 3A, 33 must remain stationary) is effected for example by means of two opposed cam-like profiles 11 and 13, one of which (for example the profile 13) is movable by a control lever 13A in such a manner to cause vertical movement of the plate between the two positions shown in FIGURES 1 and 3. The stationary members 3A, 3B, to which the profile 11 is joined, are retained against rotation by a rod 15, which is axially slidable within a seat in the body 1. The shaft 5 is axially slidable and can be driven rotationally. As in arrangements hitherto known, there is provided a sliding coupling between the shaft 5 and a bevel gear 17 which meshes with a bevel pinion 7A on the shaft 7. The control lever 13A is operable to move the shaft 5 and members 3, 3A, 3B in one axial direction and a return spring is provided which tends to maintain the two profiles 11 and 13 in contact with one another.

In the embodiment shown in the drawings, the bevel gear 17 is coaxial with and idly mounted on the shaft 5, and is rigid with a member 19 having an upper flange portion 19A and an extension 19B. The flange 19A carries a rod 21 parallel to the shaft 5 which has an end portion 21A of reduced diameter which is suitably joined to the rod 21. The shaft 5 has an extension 23 having a hole 25 whose diameter substantially corresponds to the diameter of the rod 21. The extension 23 moves axially with the shaft 5 so that when the plate 3 is in its raised position, the rod 21 extends into the hole 25 of the extension 23 and, consequently, the shaft 5 is located in a fixed angular position with respect to the member 19 and flange 19A and thus to the bevel gear 17. When the plate 3 is in its lowered position, the reduced diameter end portion 21A of the rod 21 is located in the hole 25 of the extension 23 (see FIGURES 1 and 2), and thus the shaft 5 and the plate can undergo limited angular movement with respect to the member 19, flange 19A and bevel gear 17, this movement being possible due to the differences between the diameter of the hole 25 and the reduced diameter of the end portion 21A of the rod 21.

At its upper end, the structure 1 carries a substantially annular member 27 which has two cam-profile projecting zones 29, which project radially inwardly with respect to the inner circumferential profile 27A of the member 27. On the extension 19B of the member 19,

there is provided a pivot pin 31 of a lever 33 capable of oscillatory movement and having a first arm 33A which defines a tappet which cooperates with the profiles 27A, 29, and a second arm 33B which extends into a recess 35 of a disc-like member 37 secured to the upper end of the shaft 5. A spring 39 is disposed between the member 19, which is in a stationary axial position, and the member 37, which is secured to the shaft and thus capable of being moved therewith. The spring 39 therefore urges the unit 5; 11; 3 upwardly and assures contact between the profile 11 and the profile 13. A spring 41 extends between the pin 31 (and thus the extension 19B of the member 19) and a pin 37B carried by the member 37. The spring 41 urges the arm 33B of the lever 33 towards the leading side of the recess 35 when the unit 17, 19 is rotating in the direction indicated by the arrow 1, of FIGURE 2. Therefore, as the plate 3 and shaft 5 rotate counterclockwise, the spring 41 tends to rotate the lever 33 counterclockwise around the pin 31 thus ensuring contact between the end of the arm 33A and the profile 27A, 29.

In order to effect cutting of the thread, a circular member 44 having a serrated periphery is carried by the plate 3 and the serrated member engages thread coming from each thread-guide 9 as the thread-guide is moved out of its feed position. The thread is engaged between two adjacent teeth of the member 44 and is entrained by the member during rotation until a cutting knife 46 which cooperates with the substantially radial leading edge of a tooth of the serrated member 44 effects shearing of the thread. The knife 46 is urged against the serrated periphery of the member 44 by a small spring.

In previously proposed circular knitting machines, the serrated member 44 engages a length of thread F extending between a thread-guide 9 coming out of the working and the last needle A which has engaged the thread, which length of thread is highly inclined with respect to the perpendicular to the horizontal plane containing the serrated member 44. When the thread is sheared by the stationary knife 46, a residue of thread is left which extends from the surface of the fabric, the length of which residue is defined by the length of the thread F between the point F,, at which the thread engages the serrated member 44, and the point F at which the thread engages the needle A. Owing to the high inclination of the thread F, this residue of thread extending from the surface of the fabric is relatively long, as shown by F F of FIGURE 5.

In order to avoid this disadvantage, the device shown in the drawings providesduring the stages in which the thread is to be shearedfor an advance of the serrated member 44 and thus of the plate 3 with respect to the needle cylinder after the thread (which has ceased to be fed) has engaged the teeth of the serrated member 44, and before the shearing of the thread. Then (see particularly FIGURE 1) the length of thread extending between the needle A and the serrated member 44 is not the length included between the points F and F but the relatively short length included between the points F and F (see FIGURES 1 and 5). In other words, the plate 3 together with the member 44 is rotated relative to the needle cylinder (and thus with respect to the needle A) so that the point F is advanced to the position of the point F In order to effect such relative rotation, the device is caused to move from the position shown in FIGURE 3. Firstly, the plate 3 and associated structure are lowered to the position shown in FIGURE 1. In the position shown in FIGURE 3, there is a firm angular engagement between the shaft 5 and the member 17 by means of the rod 21, but when the plate 3 together with the shaft 5 is lowered to the position shown in FIGURE 1, there is angular play between the assembly 17, 19 and the shaft 5 owing to the difference between the diameter of the hole 25 of the extension 23, which has been lowered, and the reduced diameter of the end portion 21A of the rod 21, which has not been lowered. This angular play permits a cyclic advance of the plate 3 and, in particular, the serrated member 44, after the thread F has been entrained between adjacent teeth of the serrated member, relative to the needle cylinder and other stationary structure. After shearing of the thread, the plate 3 and member 44 are returned to their original positions. The cyclic advance and return are effected by the sequential action of the camprofiles 29 and 27A on the lever member 33, which lever member 33 causes the relative angular movements between the unit 17, 19 and the unit 5, 37, 3, 44. These angular movements have maximum amplitude of angle X indicated in FIGURE .2 and this angle is defined by the angular play of the reduced diameter of the endportion 21A of the rod 21 within the hole 25 of the extension 23.

I claim:

1. In a circular knitting machine for hosiery and the like, including a rotating needle cylinder having a plu rality of needles therein, a thread guide, a welt-hooks plate mounted coaxially with the needle cylinder to rotate in synchronism therewith, a fiat member mounted on the welt-hooks plate and having a toothed periphery for engagement with a thread, to be sheared, extending between the thread guide and a needle of the needle cylinder, and a stationary blade cooperable with said toothed member to shear the thread between the thread guide and the needle of the cylinder: the improvement comprising, in combination, driving means for said welt-hooks plate including a tubular input drive shaft coaxial with said welt-hooks plate, an output drive shaft telescoped within said tubular input drive shaft and secured to said welthooks plate, and a drive coupling interconnecting said input shaft and said output shaft; said coupling including an advancing member mounted on one of said shafts for rotation therewith and operably engaged with the other of said shafts, said advancing member being movably mounted on said one shaft and operable, when moved, to advance said output shaft relative to said input shaft; stationary cam means around said Welt-hooks plate driving means cooperable with said advancing member to advance said output shaft angularly relative to said input shaft to advance said toothed member angularly relative to said needle cylinder, when the thread has been engaged by the toothed member, thereby to decrease the inclination, relative to an axial plane of the machine extending through said needle, of that portion of the thread extending from the needle to the toothed member, to shorten said thread portion; and resilient means operatively associated with said input shaft and said output shaft and biasing said output shaft away from the advanced position.

2. In a circular knitting machine for hosiery and the like, the improvement claimed in claim 1, including means operable to raise and lower said output shaft together with said welt-hooks plate thereby to move said toothed member out of and into its thread cutting position; and a locking means comprising first and second locking members secured for rotation, respectively, with said input shaft and said output shaft; said locking members cooperating, in the raised position of said welt-hooks plate, to interlock said shafts positively against relative angular displacement and, in the lowered position of said welt-hooks plate, to provide for angular displacement, relative to said input shaft, and to said advanced position, of said output shaft and said toothed member.

3. In a circular knitting machine for hosiery and the like, the improvement claimed in claim 2, in which said second locking member comprises a radial extension on said output shaft having an aperture therethrough; said first locking member comprising a rod having a main portion dimensioned to fit closely through said aperture when said welt-hooks plate is in its raised position, and having a reduced portion dimensioned to allow play of said rod within said aperture, thereby to provide for limited ad- Vance of said output shaft relative to said input shaft, when said welt-hooks plate is in its lowered position.

4. In a machine according to claim 1,

a plate secured to said output shaft for rotation therewith, said last-named plate having a peripheral slot therein,

said advancing member comprising a double-arm lever pivotally secured to said input shaft, one arm of said lever being cooperative with said cam means and the other arm of said lever engaging in said slot.

5. In a machine according to claim 1,

a thread-sucking system disposed above said welt-hooks plate and having an elongate mouth extending adjacent the position at which the thread is cut by the cutting arrangement.

References Cited UNITED STATES PATENTS Scott 66-140 Haberhaver.

Mayer.

Stack.

Kaese 66--134 Parthum.

Currier 66--134 Kaese ct a1 66-134 Great Britain.

15 W. CARTER REYNOLDS, Primary Examiner 

